Methyl red sodium salt

Methyl Red sodium salt [845-10-3] red-yellow-orange 0.05 (in water)... 

Methyl red Methyl red sodium salt Chlorophenol red Hematoxylin Litmus extra pure Bromophenol red Bromocresol purple 4-Nitrophenol Bromoxylenol blue Alizarin 4.4 t- V ... 

Dissolve 0.1 g methyl red (sodium salt) in 100 ml of 96 % ethanol Sodium thiosulphate solution ... 

Other Names C.I. Acid Red 2, sodium salt Methyl red sodium salt o-Methyl red sodium salt... 

Figure 7.12 Change of color of an ethylene-octene copolymer blend comprising 0.25 wt% PEHO-C18ImOTs and 0.04 wt% methyl red sodium salt photographs before exposure and after 20 minutes of exposure to vapors of aqueous ammonia, neutral water, and hydrochloric acid (left) UVA IS spectra recorded after 20 minutes of exposure to the respective vapors (right).

Methyl Red Sodium The sodium salt of o-carboxybenzen-eazo-dimethylaniline. An orange-brown powder. Freely soluble in cold water and in alcohol. Transition interval from pH... 

The use of methyl-orange as an indicator is based on the fact that the sodium salt in aqueous solution furnishes a yellow anion, which when treated with acids (except weak acids such as H2CO3 and H SOj) apparently gives rise to a red... 

The sodium salt of methyl red may be prepared by dissolving the crude product in an equal weight of 35 per cent, sodium hydroxide which has been diluted to 350 ml., hitoring, and evaporating under diminished pressure (Fig. II, 37, I). The resulting sodium salt forms orange leaflets. This water-soluble product is very convenient for use as an indicator. Incidentally, the toluene extraction is avoided. 

Meihylamine hydrochloride method. Place 100 g. of 24 per cent, methyl-amine solution (6) in a tared 500 ml. flask and add concentrated hydrochloric acid (about 78 ml.) until the solution is acid to methyl red. Add water to bring the total weight to 250 g., then introduce lSO g. of urea, and boil the solution gently under reflux for two and three-quarter hours, and then vigorously for 15 minutes. Cool the solution to room temperature, dissolve 55 g. of 95 per cent, sodium nitrite in it, and cool to 0°. Prepare a mixture of 300 g. of crushed ice and 50 g. of concentrated sulphuric acid in a 1500 ml. beaker surrounded by a bath of ice and salt, and add the cold methylurea - nitrite solution slowly and with mechanical stirring and at such a rate (about 1 hour) that the temperature does not rise above 0°. It is recommended that the stem of the funnel containii the methylurea - nitrite solution dip below the surface of the acid solution. The nitrosomethylurea rises to the surface as a crystalline foamy precipitate. Filter at once at the pump, and drain well. Stir the crystals into a paste with about 50 ml. of cold water, suck as dry as possible, and dry in a vacuum desiccator to constant weight. The yield is 55 g. (5). 

Properiies.—Methyl orange is the sodium salt of the sul-phoftic acid, and dissolves in water with a yellow colour. Tire fr acid is red, and its action as an indicator depends upon this change on the addition of mineral acid. 

Methyl orange Dimethylaminophenylazobenzenesulphonic acid sodium salt 2.9-46 Red Orange 3.7... 

The method may be applied to commercial boric acid, but as this material may contain ammonium salts it is necessary to add a slight excess of sodium carbonate solution and then to boil down to half-bulk to expel ammonia. Any precipitate which separates is filtered off and washed thoroughly, then the filtrate is neutralised to methyl red, and after boiling, mannitol is added, and the solution titrated with standard 0.1M sodium hydroxide solution ... 

In the direct method, a solution of the ammonium salt is treated with a solution of a strong base (e.g. sodium hydroxide) and the mixture distilled. Ammonia is quantitatively expelled, and is absorbed in an excess of standard acid. The excess of acid is back-titrated in the presence of methyl red (or methyl orange, methyl orange-indigo carmine, bromophenol blue, or bromocresol green). Each millilitre of 1M monoprotic acid consumed in the reaction is equivalent to 0.017032 g NH3 ... 

In the indirect method, the ammonium salt (other than the carbonate or bicarbonate) is boiled with a known excess of standard sodium hydroxide solution. The boiling is continued until no more ammonia escapes with the steam. The excess of sodium hydroxide is titrated with standard acid, using methyl red (or methyl orange-indigo carmine) as indicator. 

Procedure (indirect method). Weigh out accurately 0.1-0.2 g of the ammonium salt into a 500 mL Pyrex conical flask, and add 100 mL of standard 0.1M sodium hydroxide. Place a small funnel in the neck of the flask in order to prevent mechanical loss, and boil the mixture until a piece of filter paper moistened with mercury(I) nitrate solution and held in the escaping steam is no longer turned black. Cool the solution, add a few drops of methyl red, and titrate with standard 0.1M hydrochloric acid. Repeat the determination. 

FD C Red 40 6-hydroxy-5-(2-methoxy-5-methyl-4-sulfophenyl-azo)-2-naphtalenesulfonic acid sodium salt... 

Cherry and Crandall in 1932 (86) used olive oil as substrate with gum acacia as the emufsTfier. This method has served as the basis for a number of modifications that increased the stability of the emulsion, decreased incubation time and gave better precision. When a serum sample is incubated with a stabilized olive oil emulsion, lipase acts at the interface of substrate and water to hydrolyze olive oil into fatty acid plus diglycerides, and to a small extent to monoglycerides and glycerol. The bile salt sodium deoxycholate activates the reaction. These methods measure the liberated fatty acids by titration with a standardized NaOH solution. An indicator such as phenolphatalein, thymolphthalein or methyl red or a pH meter are used to detect the end point. 

Allura red AC (E 129, FD C Red No. 40, Cl Eood Red 17) is a mono azo dye that consists essentially of 6-hydroxy-5-(2-methoxy-5-methyl-4-sulfophenyl) azo-2-naphtalenesulfonic acid sodium salt (or disodium 2-hydroxy-l-(2-methoxy-5-methyl-4sufonato-phenylazo)-naphthalene-6-sulfonate). The calcium and potassium salts are also permitted. 

Methyl red serves as a convenient indicator. Slightly more than 1 mole of sodium hydroxide is required per mole of sulfur trioxide. Other metal salts can be prepared, using a suitable hydroxide or carbonate for the neutralization. 

Methyl -propyl ketone, 340 Methyl pyridines, purification of, 177-179 N-Methylpyrrole, 837, 838 Methyl red, 621, 625 sodium salt of, 626 Methyl salicylate, 780,782 Methyl sulphite, 304 2-Methylthiophene, 836 Methyl p-toluenesulphonate, 825 Methylurea, 968, 969 Methylene bromide, 300 Methylene chloride, purification of, 176 3 4-Methylenedioxycinnamic acid, 711, 719... 

Crystallization from alcohol containing a trace of acetic acid gives glistening yellow needles, melting with decomposition at about 191-1920. The red samples of hydroxynaphthoquinone often mentioned in the literature are not completely pure. Such material, or crude material of any kind, is best purified through either the sodium salt or the methyl ether. 

Another official procedure (30) involves digestion of an accurately weighed sample of saccharin in hydrochloric acid. The resulting ammonium salt is reacted with sodium hydroxide and the liberated ammonia is distilled into 0.1 N sulphuric acid. The excess of the acid is determined by titrating with sodium hydroxide using methyl red solution as indicator. 

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